1. Field of the Invention
The present invention relates to a valve assembly of a compressor, and more particularly to a valve assembly having a projection receiving the respective fixed ends of each discharge valve and backing spring.
2. Description of the Prior Art
A compressor is a device for converting the mechanical energy of compressible fluid into the compression energy of fluid. The conventional types of compressors are classified into reciprocating, rotating, and turbo models. When such a compressor is used in a refrigerator, saturated vapor having a low boiling point is converted into a high pressure state and thereafter the vapor proceeds to a condenser. For a refrigerator, the inside of the refrigerator is utilized as a cold source while the outside of the refrigerator is utilized as a hot source. In the condenser, refrigerant having high temperature and pressure emits its potential heat to the outside. The liquid phase refrigerant is transformed, via an expansion tube, into the refrigerant having low temperature and pressure in which the refrigerant then moves into an evaporator. Most of the refrigerant having low temperature and pressure absorbs the latent heat from the cold source,i.e., the inside of the refrigerator, and the refrigerant liquid phase is changed to the gaseous phase. The gaseous refrigerant flows into the compressor, the course of which comprises a refrigerating cycle. During the cycle the inside of the refrigerator constantly receives cool air, thereby achieving the required refrigerating effect.
A compressor used in a conventional household refrigerator is comprised mainly of a single stage reciprocating type. The compressor has an electric power driven motor in its housing and is installed at the lower portion of the refrigerator. The typical compressor is shown in FIGS. 3 and 4.
The compressor 10 comprises a lower case 11 and an upper case 12, in which a driving member AA and a compressing member BB are housed. A frame 24 is disposed between the driving member AA and the compressing member BB. The compressing member BB comprises a cylinder block 13 mounted on the frame 24 and a piston 14 disposed reciprocally in the cylinder block 13. By the reciprocating movement of the piston 14, refrigerant having low temperature and pressure is taken in or discharged through a valve assembly 15 disposed at the left end of the cylinder block 13 (FIG. 4). The valve assembly 15 comprises a suction valve and a discharge valve, which both constitute an elastic flapper or reed form to reduce the size of the valve assembly. The valve assembly is passively operated by the difference of pressure applied to both opposite surfaces of the valve plate.
In the reciprocating compressor, during the backward (direction of arrow A in FIG. 4) movement of the piston 14, the refrigerant having low temperature and pressure is sucked from an evaporator (not shown) into the valve assembly 15 via a suction pipe 22 and a suction muffler 16 which are sealedly attached on the upper case 12 and the lower case 11. During the forward (direction of arrow B in FIG. 4) movement of the piston 14, the refrigerant having high temperature and pressure is discharged from the valve assembly 15 via a discharge muffler 17 to a discharge pipe 23 which is sealedly attached on the lower case 11, thereby finally moving to the condenser (not shown). A refrigerant charge pipe 22' is sealedly mounted on the lower case 11 and is sealed after filling with refrigerant from the onset of production of the compressor.
However, noise of the compressor which is a major problem during the operation of refrigerator is generated from the reciprocating movement of the piston 14, shock of a closing or opening operation of the valve assembly 15, and pulsation of intaking or discharging pressure of the refrigerant, etc. Especially, since the refrigerant discharged from the small diameter pipe 22 stays in the voluminous inside of the cases (11,12) for a moment, the noise caused by the pulsation of the refrigerant. The refrigerant is intaken into the cylinder 13 through the intake muffler 16, and thus the compressed refrigerant is discharged to the discharge pipe 23 via the discharge muffler 17.
The driving member AA comprises a stator 18 installed under the frame 24 and a rotor 19 spaced from the stator 18. The rotor 19 is fixedly provided on the rotating shaft 20 which is rotatably mounted to the frame 24. At the upper end of the shaft 20 an eccentric shaft 21 is formed, which is connected to the piston 14 via both a bearing (not shown) and a connecting rod 14R. The piston 14 moves reciprocatingly within a predetermined distance, i.e., twice the eccentric distance. Further, a winding coil (not shown) connected to the stator 18 is housed in an external terminal box 18' which is sealedly mounted to the lower cases 11 through the box in which an external power source is applied.
For easier operation of the conventional compressor assembly constructed as above, an oil reservoir 25 is provided at the bottom of the lower case 11 for containing the oil. The oil is taken in through a duct or oil pump 20' extended within the shaft 20 up to the upper portion of the shaft, thereby achieving a lubrication system.
FIGS. 5 and 6 illustrate one embodiment of the conventional flapper discharge valve assembly. The valve assembly is comprised of a plate or valve member 110, a discharge valve 123, a backing spring 122, a stopper 121, and an intake suction valve 106. A detailed description of the structure and the operation of the parts described above in the valve assembly are disclosed in U.S. Pat. No. 5,209,260. The plate member 110 has a stepped recess comprising an outer surface 111, an inner surface 112, and a supporting surface 113. The discharge valve 123, the backing spring 122, and the stopper 121 are accommodated in the recess formed in multiple steps.
Furthermore, since both ends of the stopper 121 are elastically placed on the outer surface 111 and the stopper is confined by the bottom surface of a cover 101, the stopper 121 may fit loosely. The backing spring 122 and the discharge valve 123 are not elastically held in their place. Therefore, stability or reliability for closing/opening the valve is decreased. That causes a problem because noise and vibration occur so the operational life of the valve is shortened. Additionally, U.S. Pat. No. 5,178,183 illustrates the above problem of a loose fitting stopper.
Moreover, as shown in FIG. 4, since the steel material utilized is elastic and each slot formed at both ends of the stopper 121 is about 1 mm in width, an accurate sharp punch is necessary in the press operation. That causes frequent reshaping work of a worn-out punch, thereby resulting in a problem of low productivity.